DE102006039821A1 - Projection exposure apparatus for microlithography, has manipulator with linear drive, which is designed as direct drive such that lens is displaced up to specific micrometers with accuracy of ten millimeters in two degrees of freedom - Google Patents

Abstract

The apparatus has an illumination device and a projection objective. A lens is provided with a manipulator having a linear drive (11). The linear drive has an inner ring (12) and an outer mount (13), which are movable relative to one another in a direction of movement. The linear drive is designed as direct drive in such a way that the lens can be displaced up to 1.000 micrometer with an accuracy of 10 millimeter in two degrees of freedom. An independent claim is also included for a method for positioning and adjusting a lens in a projection exposure apparatus for microlithography.

Description

The The invention relates to an optical system, in particular a projection objective or a lighting system in a projection exposure machine for the Microlithography, with at least one optical element and at least a drive device having a manipulator for the optical Element, wherein the drive means at least one movable Part element and having at least one fixed sub-element, which are movable relative to each other in at least one direction of movement are, between the two sub-elements piezoelectric elements are arranged, of which a first part of a direction of action at least nearly perpendicular to a direction of movement and a second part of a direction of action in a direction of movement.

An optical system namely a projection lens of this kind is in the DE 102 25 266 A1 and in the DE 103 01 818 A described. With the drive device, which is operated with piezoelectric elements, it is possible in particular to achieve the high imaging accuracy required in microlithography by active positioning of correspondingly provided with a drive device of the type mentioned optical elements. In addition, in this way, aberrations can be corrected. This is achieved by an arrangement of stacked piezoelectric elements, wherein a part of the piezoelectric elements has its direction of action perpendicular to the direction of movement and a second part has its direction of action parallel to the direction of movement. If, for example, three stacks distributed over the circumference arranged linear actuators provided with piezoelectric elements, which are supported for example on a fixed part of the lens housing and attack with their movable sub-elements on a socket of an optical element or directly to the optical element, so can move the optical element in this way parallel to the Z-axis, that is parallel to the optical axis. With an uneven activation of the three distributed over the circumference arranged linear drives and tilting relative to the Z-axis are possible.

To the further state of the art is also on the US 2,822,133 , the US 6, 150, 750 , the DE 199 10 947 A1 and the DE 129 01 295 A1 and directed.

Of the present invention, the object is based on an optical System of the aforementioned Kind with a manipulator, which is a linear actuator with piezoelectric Elements further improve, in particular by the moves the optical element to be manipulated in more degrees of freedom can be.

According to the invention this Task solved by that in addition a third part provided with piezoelectric elements with a direction of action that is at least approximate perpendicular to the direction of action of the first part and in one Angle to the direction of action of the second part of the piezoelectric Elements lies.

A Adjustment device according to the invention for an optical Element is in claim 23 and an inventive method of manipulation of an optical element is claimed in claim 32.

By the division of the invention of the piezoelectric elements in three directions of action the shift or movement possibilities for a increased to be manipulated optical element. So are next to shifts in the Z-axis direction and tilting relative to the Z-axis as well Movements in a plane perpendicular to the Z-axis possible. On This way, in addition to Z-displacements according to the invention now also this orthogonal shifts of the optical element possible.

If is provided in an advantageous embodiment of the invention, that the angle is at least approximate perpendicular to the movement or action direction of the second part of piezoelectric elements, can be manipulated optical element very precise moving in the X / Y plane.

Around a sufficiently stable and precise Being able to reach movement should be at least three spaced stack be provided by piezoelectric elements.

If at least three spaced-apart stacks of piezoelectric Elements are provided, leaves an analogous movement in leadership reach the moving part.

A safe gradual movement of the movable sub-element is then achieved when at least six spaced apart Stack of piezoelectric elements are provided.

there can each stack with a corresponding number of piezoelectric Be provided elements that consist of all three parts and thus allow all three directions of action.

Likewise, it is also possible for each stack to provide piezoelectric elements that can be activated only in one or only in two direction of action. In this case, by an ent triggering the piezoelectric elements of the various stacks are activated in a coordinated manner.

A structurally advantageous embodiment may consist in that the movable part element between two opposite one another arranged fixed sub-elements is arranged. To this Way becomes precise guide and reached exact movement.

If in a very advantageous embodiment of the invention over the Extent of the optical element distributes at least three stacks of piezoelectric elements are provided which are independent of each other can be activated, then next The three translatory degrees of freedom in addition also three rotatory Degrees of freedom, that is a total of six degrees of freedom can be achieved. This means, that in addition also still tilts or twists around the X- / Y- or Z-axis possible become. For this it is only necessary that each of the three on the Circumference distributed arranged drive means with at least each three stacks of piezoelectric elements is provided then for Tilts or twists activated accordingly differently become.

One the main application areas of the optical system according to the invention are Projection exposure systems for microlithography and thereby projection objectives or lighting devices, because in this case accuracies in the nanometer range required are.

The Invention, however, is fundamental also as adjusting device of a general nature for the most diverse to be adjusted Suitable elements. This is especially true in cases where an adjustment with highest precision be carried out, such as measuring and testing equipment on a variety of technical areas.

advantageous Further developments and embodiments will be apparent from the others dependent claims and that in the following with reference to the drawings in principle Play.

It shows:

1 a schematic diagram of a projection exposure system for microlithography;

2 a schematic representation of a linear drive according to the invention with piezoelectric elements;

3 an enlarged view of a stack with piezoelectric elements of the 2 according to enlarged detail X;

4 a three-dimensional representation of a movable sub-element with 6 piezo stack;

5a different representations of movement levels up to 5f a movable sub-element;

6 Top view of a lens with three linear drives.

The in the 1 principle shown projection exposure system is provided for microlithography for the production of semiconductor elements. Basically, their structure is well known, which is why below only the essential parts of the invention will be discussed. For further disclosure will also be on the DE 102,25,266 A1 directed.

The projection exposure machine 1 has a lighting device 3 , An institution 4 for receiving and exact positioning of a mask provided with a grid-like structure, a so-called reticle 5 through which the later structures on a wafer 2 be determined, a facility 6 for holding, moving and exact positioning of the wafer 2 and an imaging device in the form of a projection lens 7 on.

Because the in the reticle 5 introduced structures reduced on the wafer 2 Be exposed to the imaging device 7 , namely the projection lens, very high requirements in terms of resolution and precision, being in the range of a few nanometers.

The lighting device 3 Represents one for the picture of the reticle 5 on the wafer 2 required projection beam 8th ready. As a source of radiation, a laser can be used. Through the projection beam 8th becomes an image of the reticle 5 generated and through the projection lens 7 downsized and then onto the wafer 2 transfer.

In the projection lens 7 a plurality of transmissive and / or refractive and / or diffractive optical elements, such as lenses, mirrors, prisms, end plates and the like are arranged.

One or more in the projection lens 7 arranged optical elements are with one or more manipulators 9 Mistake. A manipulator 9 is schematic in the 1 together with a lens to manipulate 10 shown schematically.

The manipulator 9 includes a linear drive as a drive device 11 through which a fixed to the optical element 10 connected movable subelement 12 , for example, the socket of the lens 10 , opposite to a fixed with the projection lens 7 connected subelement 13 can be moved. The subelement 13 For example, it may be part of the lens housing.

In the 2 to 4 is the one in the 1 only schematically illustrated drive device 11 shown in detail. As can be seen, the movable part element 12 between two opposing fixed sub-elements 13 arranged. Between the movable part element 12 and the two fixed sub-elements 13 , which may also be integrally formed, are located opposite four arranged on each side stacks 15 with piezoelectric elements 14 , The stacks 15 are arranged at a distance from each other and should be for precise guidance or displacement of the movable sub-element 12 as possible also be arranged exactly opposite on the different sides.

The construction of a pile 15 with piezoelectric elements 14 is from the 3 on an enlarged scale. As can be seen, the stack consists 15 from three parts 14a . 14b . 14c of piezoelectric elements 14 ,

The drive device 11 for example, so in the projection lens 7 be positioned so that the z-axis (optical axis) is parallel to the longitudinal axis of the stack 15 passes, bringing the X / Y plane in the plane of the movable sub-element 12 located.

Alternatively, it is also possible the drive device 11 with the movable part element 12 arrange so that the z-axis in the plane of the movable sub-element 12 located. In this case, the direction of movement lying at right angles to it is then, for example, the tangential direction in the case of a lens. For example, the second part 14b the piezoelectric elements 14 in the Z direction, and the third part 14c the piezoelectric elements 14 in the tangential direction each have its plane of action with a corresponding shear. The part responsible for a hub 14a the piezoelectric elements 14 moves in this case in the radial direction.

Further details on the mode of action and the movement of the movable sub-element 12 will be described below on the basis of 4 . 5 and 6 made.

From the enlarged view of 3 it can be seen that the first part 14a of piezoelectric elements 14 is provided with a direction of action in their activation, each in the longitudinal direction 15a of the pile 15 runs parallel. The second part 14b the piezoelectric elements 14 has with a shearing motion an action direction parallel to a predetermined direction of movement of the movable sub-element 12 on.

A third part 14c the piezoelectric elements 14 is also provided in a shearing motion with a direction of action which is perpendicular to the direction of movement of the second part 14b the piezoelectric elements 14 lies.

Of course it is also another arrangement of the three parts possible, such. B. that one Part performs a shearing motion.

The inventive design of the stacked piezoelectric elements 14 in each case three parts with different directions of action is a possibility of movement for the movable part element 12 achieved in three degrees of freedom.

4 shows an inventive embodiment with a plate-shaped rotor as a movable sub-element 12 ,

Are there six stacks? 15 arranged above and below the plate-shaped rotor (the stacks below and the fixed part element 13 are not shown), so a movement of the movable sub-element is possible both anlog, as well as in the step mode. At least six stacks per side should therefore be present, so that each three stacks can stand out for a step, while the other stacks can move and guide the moving part element safely in the displacement plane. If less accurate guidance is required or if guidance is otherwise provided, fewer stacks of piezoelectric elements may be provided on each side as desired.

In the embodiment with four stacks of piezoelectric elements 14 above and below the movement of the plane would have to be held in one step by two stacks each.

A simplified embodiment of the invention may consist in that in each case three stacks are arranged above and three stacks below the movable part element. In this case, however, a bias of the movable sub-element 12 required and the moving part 12 can only be moved by analogy. A bias voltage may be, for example, by one or more spring devices 16 , like in the 2 represented reached. As can be seen, the motion Liche subelement 12 between the two opposing fixed sub-elements 13 clamped to get a secure positioning.

In the 5a to 5f are the possibilities of movement of the movable part element 12 in different stages with 4 stacks 15 shown.

5a shows the starting point, where the subelement 12 each through the part 14a the piezoelectric elements which exert a stroke as the direction of action when activated, is clamped.

In 5b the following step is shown in the movement sequence, in which two parts 14a opened with the "Hubpiezos" and thus no longer in engagement with the moving part 12 are. The two still stuck Hubpiezos 14a hold the moving part element 12 fixed and upon activation of the part 14b The piezoelectric elements, which act as "shear moments", can initiate a movement.

From the 5c this step is evident.

5d shows the next step in the sequence of movements, with the "Hubpiezos" of the parts 14a the subelement 12 clamp again.

5e shows, similar to 5b , as now the clamping of the other two Hubpiezos the parts 14a is solved, according to which accordingly 5f the next step through an activation, similar to the one in the 5c explained, the other Scherpiezos of the parts 14b he follows.

As can be seen, this is a displacement of the movable element 12 in the direction of arrow A according to 5c and 5f ,

When activating the parts 14c of piezoelectric elements, each having a shear stroke perpendicular to the direction of action of the piezoelectric elements of the parts 14b Perform, carried out in the same way a movement of the movable sub-element 12 perpendicular to the above-described movement.

The 4 shows an intermediate link 17 that the connection between the moving part 12a and the optical element, eg the lens 10 manufactures. The intermediate link 17 may also be connected instead of a direct connection with the optical element with an inner socket in which the optical element is mounted (see dashed line with the reference numeral 20 ).

Like from the 4 is apparent, is the intermediate member 17 designed as an elastic rod to achieve a decoupling of deformations for the optical element.

Instead of an elastic rod or as additional deformation decoupling, the intermediate member 17 via a joint part 18 either with the subelement 12a or with the optical element 10 be connected. The hinge part 18 can be designed as a solid-state joint.

The 6 shows in a plan view of a lens 10 as an optical element three uniformly over the circumference of the lens arranged drive means 11 each with several stacks 15 with piezoelectric elements 14 , As can be seen grip the three intermediate links 17 according to 4 radially on the lens 10 at. With a respective activation of the third parts 14c of piezoelectric elements in the stacks 15 results in a tangential direction of action and thus a rotation of the lens 10 (see also 4 ). Upon activation of the first parts 14a there is a shift in the radial direction according to arrows B, C or D, depending on the respective in the three linear drives 11 activated parts 14a , That way, the lens can 10 be shifted in a polar coordinate system in a plane perpendicular to the Z-axis and thus to the optical axis. Of course, by mathematical conversion of the polar coordinate system with a corresponding control and regulation and a shift in an orthogonal coordinate system, namely an X / Y coordinate system.

A displacement parallel to the Z-axis is in this embodiment by the parts 14b the piezoelectric elements 14 achieved (see also 4 ).

If the three drive devices 11 are activated in different directions or partially oppositely, so are in addition to the three translational degrees of freedom for a movement of the lens 10 also three rotatory degrees of freedom and thus a total of six degrees of freedom possible. In this way, for example, twists or tiltings are possible both about the Z axis and about the X / Y axes.

As continues from the 6 can be seen, on the optical element and one or more sensors 19 be provided that the position of the lens 10 and the motion sequence upon activation of one or more of the linear actuators 11 detect. In this way, an exact control or a regulation of the movement of the lens is possible.

The sensors 19 do not have to be on the lens 10 be provided, but also at any other points, such as the movable sub-elements 12 or the pontics 17 be provided to detect the position and movement of the lens. Another possibility is to detect the position and movement of the optical element that one measures in the image itself. This means that after the projection lens, the image or wavefront is checked for aberrations.

The in the 6 illustrated storage of the lens with their adjustment practically corresponds to a bipod or hexapod storage.

As mentioned above, the optical element can be moved both analogously and stepwise. In analog mode, there are fewer stacks 15 with piezoelectric elements 14 required. The disadvantage here, however, is that only one movement within a predetermined range is possible, wherein the piezoelectric elements must always be activated to maintain a preselected or to be selected position. An advantage of this embodiment, however, is that very precise displacements and positioning are possible in this way.

The benefit of gradual shifting with a corresponding higher number of stacks 15 with piezoelectric elements 14 lies in the fact that the possibilities of movement for the optical element to be manipulated are substantially greater and that after the end of the movement, the piezoelectric elements can be at least partially deactivated.

Claims (37)

Optical system, in particular a projection objective or an illumination system in a microlithographic projection exposure apparatus, having at least one optical element and at least one manipulator for the optical element, wherein the drive device has at least one movable subelement and at least one stationary subelement which are relative to one another in at least one direction of movement are movable, wherein between the two sub-elements piezoelectric elements are arranged, of which a first part has an action direction at least approximately perpendicular to a direction of movement and a second part of a direction of action in a direction of movement, characterized in that in addition a third part ( 14c ) with piezoelectric elements ( 14 ) is provided with a direction of action which is at least approximately perpendicular to the direction of action of the first part ( 14a ) and at an angle to the direction of action of the second part ( 14b ) of the piezoelectric elements ( 14 ) lies. Optical system according to claim 1, characterized in that the angle of the third part ( 14c ) at least approximately at right angles to the direction of action of the second part ( 14b ) of piezoelectric elements ( 14 ) lies. Optical system according to claim 1 or 2, characterized in that at least three spaced-apart stacks ( 15 ) of piezoelectric elements ( 14 ) are provided. Optical system according to claim 1, 2 or 3, characterized in that at least three stacks ( 15 ) of piezoelectric elements ( 14 ) are provided for an analogue movement. Optical system according to one of claims 1 to 4, characterized in that at least six stacks ( 15 ) of piezoelectric elements ( 14 ) for a stepwise movement of the movable sub-element ( 12 ) are provided. Optical system according to claim 3, 4 or 5, characterized in that each stack ( 15 ) of piezoelectric elements ( 14 ) with all three parts ( 14a . 14b . 14c ) of piezoelectric elements ( 14 ), which are activated in different directions of movement is provided. Optical system according to claims 3, 4 or 5, characterized in that in each stack ( 15 ) piezoelectric elements ( 14 ) are provided for only one or only two directions of movement. Optical system according to one of claims 1 to 7, characterized in that the movable subelement ( 12 ) between two fixed subelements ( 13 ) is arranged. Optical system according to claim 8, characterized in that the movable subelement ( 12 ) between two opposing fixed sub-elements ( 13 ) is arranged. Optical system according to one of claims 1 to 9, characterized in that the movable sub-element ( 12 ) on the optical element ( 10 ), on a version ( 20 ), to which the optical element is connected, or is arranged on a part connected to the optical element or with the socket. Optical system according to claim 10, characterized in that with the optical Element ( 10 ) or associated with the socket part as a lever-like intermediate member ( 17 ) is trained. Optical system according to claim 11, characterized in that the intermediate member ( 17 ) is elastic. Optical system according to claim 11, characterized in that the intermediate member ( 17 ) with at least one joint part ( 18 ) is provided. Optical system according to claim 13, characterized in that the joint part ( 18 ) is designed as a solid-body joint. Optical system according to one of claims 1 to 14, characterized in that a plurality of drive devices ( 11 ) each having at least one movable sub-element ( 12 ) and at least one fixed subelement ( 13 ) on the optical element ( 10 ) or the version ( 20 ) for the optical element ( 10 ) are arranged so that for the movement of the optical element ( 10 ) give multiple degrees of freedom. Optical system according to claim 15, characterized that six degrees of freedom are provided. Optical system according to claim 15 or 16, characterized in that at least three drive devices ( 11 ) each having a movable sub-element ( 12 ) and a fixed subelement ( 13 ) over the circumference of the optical element ( 10 ) or the version ( 20 ) are provided distributed. Optical system according to one of claims 1 to 17, characterized in that the at least one fixed subelement ( 13 ) a housing part of a projection objective ( 7 ). Optical system according to one of claims 1 to 18, characterized in that as piezoelectric elements ( 14 ) Piezo actuators are provided which generate a stroke or shear when activated. Optical system according to one of claims 1 to 19, characterized in that the at least one movable subelement ( 12 ) with respect to the at least one fixed subelement ( 13 ) is biased. Optical system according to claim 20, characterized in that for a bias voltage at least one spring device ( 16 ) is provided. Optical system according to one of claims 1 to 21, characterized in that for determining the position of the at least one movable sub-element ( 12 ) one or more sensors ( 19 ) are provided. Optical system according to one of claims 1 to 21, characterized in that sensors to the optical element ( 10 ), on the version ( 20 ) or provided with the socket associated part. Adjusting device for an optical element to be adjusted in an imaging device, in particular in a projection objective or illumination device in a microlithographic projection exposure apparatus, wherein the optical element to be adjusted is provided with at least one manipulator having a drive device, wherein the drive device comprises at least one movable subelement and at least a fixed sub-element, which are movable relative to each other in at least one direction of movement, wherein between the two sub-elements piezoelectric elements are arranged, of which a first part an action direction at least approximately perpendicular to a direction of movement and a second part has a direction of action in a direction of movement characterized in that in addition a third part ( 14c ) with piezoelectric elements ( 14 ) is provided with a direction of action which is at least approximately perpendicular to the direction of action of the first part ( 14a ) and at an angle to the direction of action of the second part ( 14b ) of the piezoelectric elements ( 14 ) lies. Adjusting device according to claim 23, characterized in that the angle of the third part ( 14c ) at least approximately at right angles to the direction of action of the second part ( 14b ) of piezoelectric elements ( 14 ) lies. Adjusting device according to claim 23 or 24, characterized in that at least three spaced from each other stack ( 15 ) of piezoelectric elements ( 14 ) are provided. Adjusting device according to claim 23 or 24, characterized in that at least three staggered stacks ( 15 ) of piezoelectric elements ( 14 ) are provided for an analogue movement. Adjusting device according to one of claims 23 to 26, characterized in that at least six spaced apart stack ( 15 ) of piezoelectric elements ( 14 ) for a stepwise movement of the movable sub-element ( 12 ) are provided. Adjusting device according to one of claims 25 to 27, characterized in that each stack ( 15 ) of piezoelectric elements ( 14 ) with all three parts ( 14a . 14b . 14c ) of piezoelectric elements ( 14 ), which are activated in different directions of movement is provided. Adjusting device according to one of claims 25 to 27, characterized in that in each stack ( 15 ) piezoelectric elements are provided for only one or only two directions of movement. Adjusting device according to one of claims 23 to 29, characterized in that the movable part element ( 12 ) between two fixed subelements ( 13 ) is arranged. Adjusting device according to claim 30, characterized in that the movable part element ( 12 ) between two opposing fixed sub-elements ( 13 ) is arranged. Method for positioning and adjusting an optical element in an optical system, in particular in a projection objective in a microlithographic projection exposure apparatus, wherein the optical element is acted upon by at least one manipulator having a drive device by piezoelectric elements which act on at least one movable subelement of the at least one drive device and the at least one movable subelement being displaced and positioned relative to at least one fixed subelement of the drive device by a first part of piezoelectric elements having an action direction at least approximately perpendicular to a direction of movement and by a second part of piezoelectric elements having an action direction in a direction of movement characterized in that by a third part ( 14c ) of piezoelectric elements ( 14 ) with a direction of action which is at least approximately perpendicular to the direction of action of the first part ( 14a ) and at an angle to the direction of action of the second part ( 14b ) of the piezoelectric elements ( 14 ), the movable subelement ( 12 ) is moved in two different directions of movement. Method according to claim 32, characterized in that the third part ( 14c ) of piezoelectric elements ( 14 ) movement at an angle at least approximately at right angles to the direction of movement of the second part ( 14b ) of piezoelectric elements ( 14 ) generated. A method according to claim 32 or 33, characterized in that a movement of the optical element to be adjusted ( 10 ) by at least three stacks ( 15 ) of piezoelectric elements ( 14 ) is made. Method according to claim 34, characterized in that the at least three drive devices ( 11 ) so over the circumference of the optical element ( 10 ) are arranged so that in dependence on the activation of the piezoelectric elements ( 14 ) several degrees of freedom for adjustment and positioning of the optical element ( 10 ). Process according to claim 35, characterized in that that the adjustment and positioning in six degrees of freedom he follows.